Today, telephones are very frequently used and it is common that a caller calling a large company is placed in a call queue where the caller has to wait until someone is ready to talk to the caller. There are a variety of telephone exchange systems developed to handle such call queues. There also exist so-called “call-back”systems, such that a caller need not wait in a call queue, but may instead chose when he wants to be called back. Such systems are large, complex and expensive.
Also, a private person or a small business may sometimes be busy (e.g. on the phone or in a meeting with a customer/patient) when a caller calls. It is then desirable to be able to notify the caller without having to interrupt an ongoing activity without having to obtain and install a telephone exchange that can cope such a function.
There are today a few solutions which are usable for private persons or small businesses, such as answering machines and caller identifiers. An answering machine gives the called party a possibility to notify a caller a preselected message. A caller identifier gives the called party a possibility to see who has called and when. These solutions are not particularly flexible, which is a problem for a person who uses telephony a lot.